In architecture, when demarcating moldings and leveling the ceiling with the ground, keeping a tilt meter horizontal to the ground all the time is an important issue. At present, bubble levels are most often employed to do leveling, but the situation of inaccurate readings often happens when doing leveling with bubble levels.
FIG. 1 illustrates a schematic diagram of a conventional leveling device in a tilt meter. As shown in FIG. 1, the plumb 101 is always perpendicular to the horizontal by gravity. Such a tilt meter can be used on any kind of ground, and since the plumb 101 is always perpendicular to the horizontal by gravity, the laser scanning apparatus associated with the plumb can indicate the horizontal status precisely. Although determining the horizontal by the plumb is a simple and effective method, the horizontal status only can be measured until the swinging plumbtakes some time to be still. The usefulness of this kind of leveling device is therefore not optimum.
Another kind of laser tilt meter exists which determines the horizontal by using a level-measuring circuit comprising a tilt sensor, which associates with a laser transmitter to cast horizontal rays of light. Tilt sensors can be classified into two kinds. One is the single axis tilt sensor, and the other is the dual axis tilt sensor. The single axis tilt sensor measures the slant of one direction, whereas the dual axis one estimates the slant of a plane.
The principle of how the tilt sensor works is illustrated in FIG. 2. It is known that the conductivity between two electrodes is proportional to the length of electrode immersed in an electrolyte. As ground is not in horizontal status, the surface of the electrolyte in the tilt sensor remains level due to gravity. The electrolyte is electrically conductive, and since the conductivity between the two electrodes is proportional to the length of electrode immersed in the electrolyte, the resistance changes in proportion to the tilt angle. Therefore, the slant of the tilt sensor is derived from the resistance corresponding to the tilt angle.
FIG. 3 illustrates the input method of a dual axis tilt sensor. Four outer electrodes, A, B, C and D, are placed in a crisscross arrangement as signal inputs, and both axes share the center electrode O as a signal output. In the tilt sensor 301, electrodes A and B are signal inputs, electrodes C and D are grounded, and electrode O is the signal output, wherein electrodes A and C represent the input of one direction and electrodes B and D represent the input of the other direction. A switch (not shown in the drawing) is further included in the tilt sensor 301 to completely disconnect one axis while the other is active. Additionally, to prevent the electrolyte of the tilt sensor 301 be electrolyzed, the DC components of the input signals must be zero. Therefore, symmetric square waveforms are used to be the input signals.